Spark plug



Jan. 19, 1937. L; F. uggER SPARK mm Filed Oct. 2, 1934 Patented 1,... 19, 1937 UNITED STATES; v

v 7 2,068,030 if}; SPARK PLUG/ Y Leo F. ne Esther-ville, m Application October 2, mesa-mus. 746,565" I e 2 Claims, (Cl. 123-169) This invention relates to spark plugs for jump spark ignition systems. I

A primaryobject of the invention is toproducea spark plug which will fire under obstinate'oil 5 fouling conditions and under very high pressure.

Anotherobject of the invention is'to'so construct a plug of this character that the inside will be kept clean and unfouled and in which the full surface of both electrodes will be used thus inducing a very hot spark. v

Still another object is to. construct a" spark plug in which the capacity of the compression chamber is'decreased and 'a'full ring fire spark created. 1

1 Another object is to construct aspark plug of this type having a spherical lower' end or tip so A that the twoelectrodes are at the peak "or vertex. of a sphere and thus accomplish a perfect spark.

lower end providing an internal resistance of its own against the motor compressionand Ither'" keeping the inside of the plug clean. j l

-In carrying outthesel objects the invention is susceptible of, modifications without departing; from thespirit or sacrificing any of theadvan-j tages of theclaimed invention; j'

' In the accompanying drawingz d. J

1 represents a side. eleyatiom partly in section ofa spark plug embodying this inve nti on; v

Fig. 2 is a bottom plan -viewthereof 80 j Fig. 3 is a detailsecti na'l view thruthe e lec-.

trodes, showing a slightly different formy-and Fig.4 is a'similar-l-view-oi still another form. 1 In the embodiment illustrateda spa'rkyplug l 35' is shown including the usual shell l withpn exsince the jump spark 'of high tensioned' voltage;

plugs is best accomplished thru spheres, the spark leaving sameat'the vertex. This cap, 10 has itsouter rounded surface cut awayat 12 at opposite sides ,tofcrm a grip for manipulating the cap to screw it into and out of the neck to insure correct adjustment for diiferent sparkgaps and for removing the cap in case of repair. This cap H) which forms the lower end of the plug and encircles the electrode 5 provides a closed plug end producing an internal resistance of its own against themotor compression thereby keeping the inside of the plug clean and unfouled, and also pausing Another 'obj ect'is toform aplug having a closed I 5 Ta. portionof an, electrode, threaded cap engaged with the interior screwa decreasedcapacity of the compression chamberand creates a full 'ring fire spark entirely aroundv 'thecent'ral electrode." -,'I'hus thefull surface of both electrodes is used "inducing-a very hot spark. It will thus be seenthat this is why this particular plug will fire-under'obstinate oil fouling conditions since the oil cannot get to the interior of the plug.

This plug will fire under very great pressure much beyond that where ordinary plugs cease. It is to be understood that the cap 10 has a tight screw'connection with the neck 2 so that it will remain in adjusted position.

In Fig. 3 the aperture in the adjustable cap is shown ,flared to vary the spark gap; while in the form shown inFig. 4 both the opening and the pin are shown inclined for this purpose, the opening I,claim as my invention:

' i, 1." Ina" spark plug the combination of a shell nteriorly screw -threaded at its inner end forming an exteriorly screwthreads of the shell and completing the electrode,

' the cap having an orifice centrally located and gradually enlarging from the outer surface of the capto the inner surface of the cap, an insulator within the shell, and a second electrode within theiinsulatc'r having a projecting tapered end located centrally inthe orifice of the cap, the end of. the inner electrode and thewall of the gradually enlarged orifice in the caha'presenting differentially tapering surfaces whereby the sparkgap between the tapered electrode and the wall of the orifice in the cap may be decreased or increased by screwing inwardly or screwing out-'- wardly the cap.

2. Ina spark-plug the combination of a shell screw-threaded interiorly and exteriorly at its inner end, an insulator longitudinally located and the wall of the gradually enlarged-orifice in the cap presenting "differentially tapering sur=- 1 faces diametrically opposite portions of the exterior-surface of the capbeing flattened to accommodate a manipulating tool whereby thesparkgap 'may be varied by screwing inwardly or outwardly the heml-spherical cap.

n. LIEBER. 

